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Simultaneous electrochemical detection of benzimidazole fungicides carbendazim and thiabendazole using a novel nano-hybrid material modi#ed electrode Yuanyuan Dong, Lijun Yang, and Lei Zhang J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.6b04675 • Publication Date (Web): 09 Jan 2017 Downloaded from http://pubs.acs.org on January 12, 2017
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Journal of Agricultural and Food Chemistry
Simultaneous electrochemical detection of benzimidazole fungicides
1 2
carbendazim and thiabendazole using a novel nano-hybrid material
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modified electrode
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Yuanyuan Dong, Lijun Yang, Lei Zhang∗
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College of Chemistry, Liaoning University, 66 Chongshan Middle Road, Shenyang,Liaoning,
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110036, People’s Republic of China
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Abstract:
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In this work, a novel ZnFe2O4/SWCNTs nano-hybrid was successfully
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synthesized as electrode materials and applied to the simultaneous quantitative
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determination of carbendazim (CBZ) and thiabendazole (TBZ). The electrochemical
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behaviors of CBZ and TBZ on the ZnFe2O4/SWCNTs/GCE were investigated using
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cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The
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electrochemical active area of modified electrode was calculated, which is nearly 5.5
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times that of the bare electrode. The influence of various factors such as accumulation
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time, pH and scan rates, type of surfactant, and the electrochemical reaction
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mechanism were studied. The results showed that the reaction of CBZ/TBZ was
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controlled by adsorption/diffusion and was a quasi-reversible/an irreversible process
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at the ZnFe2O4/SWCNTs/GCE. In the pH 7.0 phosphate-buffered saline (PBS)
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containing 10.0 µg/mL CTAB, the electrochemical responses of CBZ and TBZ were
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separately investigated and were linearly dependent on their concentrations range
*
Corresponding author. Tel.: +86 24 62207809; Fax: +86 24 62202380. E-mail address:
[email protected] (L. Zhang). 1
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from 0.5 to 100.0 µM, with relatively low detection limits of 0.09 µM and 0.05 µM,
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respectively. The concentration range for the simultaneous determination of CBZ and
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TBZ was 1.0-100.0 µM. Furthermore, with satisfactory results, the proposed
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electrochemical sensor was successfully applied to the determination of CBZ and
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TBZ in the real samples.
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Keywords:
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determination.
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Introduction
Carbendazim;
Thiabendazole;
ZnFe2O4/SWCNTs;
Simultaneous
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It is well known that there are a multitude of potential pollutants in foods,
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including different types of pesticides, mycotoxins and so on. CBZ and TBZ are
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primary compounds of the benzimidazole fungicides which are generally used in the
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crops to protect vegetables and fruits from a range of fungus and pests and provide
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quality preservation.1, 2 Most of these compounds are present in the environment after
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their use, and even some residues remain for a long time because it is difficult to
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break the ring structure of the benzimidazole.3 As a result, their residues can be also
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found in foods and environment water, which might pose a potential risk for human
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health due to their toxicity, as demonstrated by several studies.4 Hence, fungicides
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analysis in fruits/vegetables and water is of particular importance because different
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pesticides are used by planters to prevent the diverse pests and post-harvest spoilage.
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For this reason, numerous legislations on maximum residue limits (MRLs) for raw
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foods have been established, which range from 0.05 to 15.0 mg/kg for CBZ/TBZ
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depending on the different foods (such as fruits like oranges, apples, the MRL is 5.0 2
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Journal of Agricultural and Food Chemistry
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mg/kg, and the MRL of mushrooms is 1.0 mg/kg, etc.).5, 6 Consequently, the ability to
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accurately and rapidly detect trace amounts of pesticides has become more and more
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important for the health and environment protection.
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High sensitive high-performance liquid chromatography (HPLC) methods allow
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the determination of trace benzimidazole fungicides in foods.7-9 However, the HPLC
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method is more expensive and not suitable for the in situ analysis of benzimidazole
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fungicides. 10, 11 As an alternative to HPLC techniques, the electrochemical method
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has been accepted as one of the most effective tools due to its good sensitivity, low
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cost, short analytical time and easy portability.12,
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usually coexist in the same system and interfere with each other due to their similar
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structures, characteristics, and physicochemical property.14 Therefore, it is very
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interesting but it remains an important challenge for the highly sensitive and
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simultaneous electrochemical determination of CBZ and TBZ.
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Nevertheless, CBZ and TBZ
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In recent years, for the development of sensitive CBZ or TBZ, electrochemical
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sensors and some functional nanomaterials have been used. Among them, carbon
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nanotubes (CNTs) 15, 16 and their hybrids are typical examples, such as conducting
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polymer/MWCNTs modified GCE,17 mesoporous silica/MWCNTs modified-GCE,18
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MWCNT/polymeric methyl red modified-GCE,19 and cyclodextrin/graphene hybrid
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nanosheet modified GCE.20 The electrochemical response of CBZ or TBZ have been
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improved by the above mentioned sensors. However, these methods have only been
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used for the detection of individual compounds rather than for their simultaneous
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analysis. The rationally design of new sensing materials is still an urgent need to 3
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further improve the development of highly sensitive multi-pesticides sensing
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platform.
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Spinel ferrites nanoparticles (MFe2O4, M = Ni, Cu, Zn, Co, Mn) provide
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important levels of new functionality for electrochemistry owing to their greater
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electronic
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electrochemical activity.21 Among them, ZnFe2O4 might be a promising electrode
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modifier due to its low toxicity, low cost and easy preparation. Moreover, Zn and Fe
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have excellent electrocatalytic activity which can improve electrochemical properties
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of CNTs.22 Although many investigators have reported the preparation methods of
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magnetic CNTs and their applications in many fields, only a few of them have applied
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these composites to electrochemical sensors.23-25
conductivity,
effective
mass
transport,
high
surface
area
and
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In this work, ZnFe2O4/SWCNTs nano-hybrid has been successfully designed and
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synthesized through a facile one-step hydrothermal method and used as a modified
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electrode material for simultaneous determination of CBZ and TBZ. Meanwhile, the
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experimental results indicated that the voltammetric responses of CBZ and TBZ were
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found to be greatly enhanced in the presence of CTAB. The combination of SWCNTs
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with ZnFe2O4 can provide excellent electrochemical platforms for two benzimidazole
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fungicides due to the combination of strong adsorptive capability and enlarged active
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surface area in the real samples analysis.
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Experiment.
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Reagents and chemicals. SWCNTs (length: 5−30 µm; specific surface
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area: >380 m2/g; outer diameter:
